Effectiveness of cognitive behavioral therapy for adult mental disorders: A large-scale naturalistic study across 29 university outpatient clinics

Abstract

Practice-based evidence has emerged as an important complementary paradigm to studies in controlled trials. This paper presents results of a large research-practice network at German university outpatient clinics; the KODAP initiative. Pre-post effect sizes, direct assessments of change, and rates of clinically significant and reliable improvement are reported in a heterogeneous clinical sample of 6624 adult patients treated between 2023 and 2014 in 29 psychotherapeutic outpatient clinics. Clinical diagnoses, determined with structured diagnostic clinical interviews at baseline across all clinics, encompassed a wide range of psychopathology. Effectiveness was comparable to other studies in naturalistic settings (d ≈ 0.75–0.95) and somewhat lower than changes reported in disorder-specific CBT efficacy trials. In direct assessments of change, only 1.9% of the patients reported symptom worsening and 3.4% reported no change during treatment. Overall, the results show the potential of multi-site naturalistic research initiatives in general and the effectiveness of outpatient CBT at German university outpatient clinics in particular.